Make ResourceFetcher return Resources with LoadError instead of nullptrs.

third_party/WebKit/Source/core/fetch/ResourceFetcher.h

 /*
     Copyright (C) 1998 Lars Knoll (knoll@mpi-hd.mpg.de)
     Copyright (C) 2001 Dirk Mueller <mueller@kde.org>
     Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011 Apple Inc. All
     rights reserved.
     Copyright (C) 2009 Torch Mobile Inc. http://www.torchmobile.com/
 
     This library is free software; you can redistribute it and/or
     modify it under the terms of the GNU Library General Public
     License as published by the Free Software Foundation; either
@@ skipping 172 matching lines @@
                                      const String& charset,
                                      const ResourceFactory&);
   void storeResourceTimingInitiatorInformation(Resource*);
   ResourceLoadPriority computeLoadPriority(Resource::Type,
                                            const FetchRequest&,
                                            ResourcePriority::VisibilityStatus);
 
   Resource* resourceForStaticData(const FetchRequest&,
                                   const ResourceFactory&,
                                   const SubstituteData&);
+  Resource* resourceForBlockedRequest(const FetchRequest&,
+                                      const ResourceFactory&);
 
   // RevalidationPolicy enum values are used in UMAs https://crbug.com/579496.
   enum RevalidationPolicy { Use, Revalidate, Reload, Load };
   RevalidationPolicy determineRevalidationPolicy(Resource::Type,
                                                  const FetchRequest&,
                                                  Resource* existingResource,
                                                  bool isStaticData) const;
 
   void moveCachedNonBlockingResourceToBlocking(Resource*, const FetchRequest&);
   void moveResourceLoaderToNonBlocking(ResourceLoader*);
@@ skipping 84 matching lines @@
   }
 
  private:
   Member<ResourceFetcher> m_loader;
   bool m_previousState;
 };
 
 }  // namespace blink
 
 #endif  // ResourceFetcher_h